Generally, a vehicle provided with a sliding door has a structure in which the door is slid to be as close as possible to a vehicle body when opening to improve convenience in getting on and getting off the vehicle in a narrow space.
As shown in FIGS. 1 and 2, a sliding door of a vehicle according to the prior art includes a vehicle body 100 provided with a door opening part 200 to be opened or closed by sliding of a door 400 to allow a passenger to get on or get off the vehicle therethrough; a rail 300 provided in the vehicle body 100 in order to slide the door 400; a roller 500 inserted into the rail 300 provided in the vehicle body 100; and an arm 600 with one side fixed to the door 400 and the other side supporting the roller 500. The rail 300 includes an upper rail 301 provided in the vehicle body 100 adjacent to an upper side of the door opening part 200, a lower rail 303 provided in the vehicle body 100 adjacent to a lower side of the door opening part 200, and a center rail 302 disposed at the rear of the vehicle body 100 and extended in a length direction of the vehicle on an outer surface of the vehicle body 100. An operation of the sliding door is regulated according to a layout of the rail 300 described above.
However, the sliding door according to the prior art as described above has problems in that a structure of the door opening part 200 of the vehicle body 100 becomes complicated by the rail 300, the center rail 302 is provided on the outer surface of the vehicle body 100, such that an appearance of the vehicle is deteriorated, and many design restrictions are present in the vehicle due to the rail.